Magnetic relaxation effects in PbMo₆S₈ superconducting single crystals: A comparison with high-T_c superconductors

Magnetic measurements performed on PbMo6S8 single crystals show that this classic isotropic superconductor (Tc = 14.5 K) presents surprisingly similar irreversibility and relaxation properties as those generally attributed to layered high-Tc superconductors. An irreversibility line H* = H*0(1-t)m with m∼ 3 2 is observed for H {less-than or approximate} 1 kOe. From the magnetic relaxation rates measured below this irreversibility line, activation energies U0 around 15 meV are derived within the flux creep picture. The similarity with the high-Tc oxides is explained by the very short coherence length ξ ≈ 25 Å of PbMo6S8 which also makes this compound sensitive to disorder and local defects. © 1990.